Tho Supremo Court decided a very important important cause to-day, .involving the freedom of all the French slaves now in existence In this State. It was between Joseph, a man of color, and Jarrot; and was anappeal by tho former from a decision rendered by the St. Clair Circuit Court against bis right to liberty. It wns argued a year ago, and has boon, under advisement ever since, until its decision to-day. The opinion was given by Judge Young, wherein it is settled that all slaves who are tho offspring of French slaves bom in this State since the adoption of our Constitution; are free. This will icnrly do 'away r with every thine; like slavery in Illinois; and all that is to bo ro- grettcd is, thlt the opinion was not unani- nous. The Judges stood soven to two— Justices Shields and Treat, dissenting'